Genetic strategies for the analysis of childhood behavioral traits

Genetic strategies appropriate for the analysis of childhood behavioral traits are reviewed. The problem of etiologic heterogeneity is discussed, and suggestions for minimizing its effect are offered. Two traits, stuttering and Tourette syndrome, are given as examples to illustrate methodologies useful for the genetic analysis of childhood disorders. In both examples, it is shown that the disorder clusters in families, that it is vertically transmitted, and that the transmission is sex-modified. Several genetic models can explain the pattern of transmission, although cultural hypotheses also should be considered. Hence, additional analyses need to be attempted to help clarify the modes of transmission and the factors involved.